Large Angle Reorientation of a Solar Sail Using Gimballed Mass Control
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Large Angle Reorientation of a Solar Sail Using Gimballed Mass Control E. Sperber1 · B. Fu1 · F. O. Eke1
© American Astronautical Society 2016
Abstract This paper proposes a control strategy for the large angle reorientation of a solar sail equipped with a gimballed mass. The algorithm consists of a first stage that manipulates the gimbal angle in order to minimize the attitude error about a single principal axis. Once certain termination conditions are reached, a regulator is employed that selects a single gimbal angle for minimizing both the residual attitude error concomitantly with the body rate. Because the force due to the specular reflection of radiation is always directed along a reflector’s surface normal, this form of thrust vector control cannot generate torques about an axis normal to the plane of the sail. Thus, in order to achieve three-axis control authority a 1-2-1 or 2-1-2 sequence of rotations about principal axes is performed. The control algorithm is implemented directly in-line with the nonlinear equations of motion and key performance characteristics are identified. Keywords Solar sails · Spacecraft attitude dynamics · Spacecraft attitude control
Introduction A solar sail is a space vehicle that utilizes solar radiation pressure in order to generate forces used for thrust and attitude control. Solar sail flight is characterized by low-thrust, high-impulse acceleration. At any given moment, the resultant of the solar radiation pressure forces acting on a sailcraft and distributed over the sail surface
E. Sperber
[email protected] 1
Department of Mechanical and Aerospace Engineering, UC Davis, One Shields Ave, Davis, CA 95616, USA
J of Astronaut Sci
is small. However, because this net force acts continuously on the craft, significant velocity changes can be achieved over time. Depending on a spacecraft’s mission objectives, fuel-free, high-impulse propulsion may offer a number of advantages over conventional methods for generating thrust. For example, sailcraft have been proposed for missions involving non-inertial and highly non-Keplerian orbits, innersolar system sample return missions, as well as outer-solar system planetary flybys [1]. A variety of sailcraft sizes and geometries have been proposed each with its own benefits and specific engineering challenges. A rigid-type sailcraft consists of a reflective membrane stretched between structural support spars radiating from a central bus. The bus houses navigation and control subsystems, cargo or payload, and other scientific instruments. This configuration is thought to be the most feasible for near-term mission applications [2]. A spin-type sailcraft lacks the structural support of a rigid sailcraft and instead keeps its membrane deployed by spinning it about a central axis. In addition to maintaining its shape, spinning the membrane provides a small amount of rotational inertia useful in attitude stabilization. Heliogyro sailcraft are equipped with long reflective blades radiating from the central bus. These blades have minimal
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